Process for making phosphoric acid.



y J. W. BURIIOUGHS. PROCESS FOR MAKING PHOSPHORIC CID.

APPLICATION FILED MAR. 18I9I4.

Patented June 8, 1915.

5 vw@ nto@ posed o iin sTaTus PATENT ourson.

. .ramas w. nu'nnouens, or rnvrNG'roN, New Yoan.

I PROCESS FOR MAKING- PHOSPHORIC ACID.

Specieation of Letters Patent.

vApplication ledlarch 18, 1914. Serial No. 825,492.

T0 all whom it may concern Be it known that I, JAMES W. BURnoUGHs, a citizen of the United States, residing at Irvington, in the county of Westchester4 and State of New York, have inventedy new and useful Improvements in Processes for Making Phosphoric Acid, of which the followin is-a specification. v i

his invention relates to the preparation of phosphoric acid and my apparatus and Y process are most conveniently operated in con]unet1on with a furnacefsuch as an elec- ,tric furnace in which phosphate rock is used as araw material. -It is usualin such furneces to-heat .the phosphate rock with a flux such'as Sandor other silicious material. The

gasesare com osed of phosphorus and silica. .n A principa lobject of my invention is to provide simple process for effectivelysep- Aaatislgt e'fphosphorus from the silicious or edients of; the gas,.and to collect calci in the phos hor-us with asv little waste as possible of. p osphorus inthe waste gases which compose the'gas and'absorb the phosphorus.

In these'ztowers there isl a continual deposit of calcareous silicious compounds or sand which eventually clogs up the passages and makes it necessary to overhaul and clean the tower. In these towers also there appears to be 'another de osit in addition to the silica or sand re erred to above,'and this deposit-to-which I now refer includes a considerable quantity of phosphorus in an insoluble state, whioh isvlost for all intents and purposes of the process, that isvv it is not carried off with the absorption Water as should be.

One of the objects of my invention is to overcome these defects in operation of absorption towers, and to provide a process whereby the phosphorus is more effectively separated from the gas; and in which the 'process may be continuously carried on.

'depositories which may constitute a feature My invention resides in the process tobe described more fully hereinafter.

In the drawing, which represents one embodiment of my apparatus Figure 1 is a side `elevation diagrammatically illustrating. a 06 container in which the gas is received from the furnace. Fig. 2 is ya-plan of thecontalner shown in Fig. 1. VFig. 3 is a longitudinal section through the container. Fig. ,4 1s a vertical cross section through the con- 65 tainer. Fig. 5 is a .vertical section taken through a. part of the container and illustrating the preferred manner of supporting of the invention. l

A gas having such a compositionfasthat described, in cooling, will arrive at a certain temperature beyond which the phosphorus will not be eliminated by the decomposing agent, and this I believeis the reason for the deposit in absorption towers of phosphorus in a form whichisnot soluble or decomposable by the water. According to my process I maintain, the tem eratureof the body or entire volume of t e as above a pedte'rmined point wl im rom 700 to 9 0 egrees centigra e, n upon circumstances, such as theispeed of' driving the fan. and the temperatureof the incoming gases, etc. I `cool the 'molecules-of the gas 85 locally at a plurality of points, but prevent` the body of he gas falling below this pre-1 determined point, namely 700. to 900 degrees centigrade.

my process comprises a container l0, which is preferably of elongated' form Vand arranged so that the gisfmovesthrough it in a column, said gas eing admitted from a The preferred appara us forcarrying out furnace, part of whichl is indicated at 11.

The' column 'of gas is drawnY through the container preferably .by means of. an exhaust. n

fan connected tosan o1 et 12.

I cause a clrculatioxror relative movement among the molecules bf the gas in passing 190 through the container and'cool them lin the presence efwater, ,which decomposes the gas. This is preferably effected by causingl the gases to pass through a tortuous path.

I provideA depositories in the path of the gas which are -jiireferably inthe form of metal plates 13 which extend outward alternately from the opposite side walls ofthe container.l A sludge containing phosphorus will collect on the depositories. The bottom ilo Patented June e, 1915.

'14 of the container is preferably slightly dished so; as to collect the sludge which forms on the depositories,..and'at a short v distance above the bottom an overflowll is arranged fortlie sludge. The level of this overflow lis slightly above the lower edges of the plates or depositories 13 so as to form' a seal or trap'under-the plates, and force the gases to pass to and frein a horizontal plane around the vertical edges yof the plate in suc! cession. This overflow 15 extends vdown- Wardly into a sludgel tank 17 in which its delivery mouth 16 is depressed so that the lsludge or acid in the tank forms an air seal '.or trap `,to prevent entrance of. air into the.

container at this point. I`may simply let the Water-,drip throughthe horizontally advancing column of gas toreduce its ternperature locally. v

The baille plates areintended to operate as'locally cooled points in Contact With which the molecules of the gas come as they pass through thecontainer, for I have discovered that if this hot calcareous or .sili- -c'ious phosphoricgas is cooled in the presence 'of a substance such as Water the oxid of: phosphorus Will combine with or be abl-sorbed'by the Water, and form a silicious sludge. This sludge tends to form on 'or collect upon the depositories 13 and these plates ordepositories Will drain into the 'common collecting point or 'dish 18 at the bottom. A -f I'prefer to use Waterto Abreak upy the gas,

Iand this is preferably introduced by injecting it Within the gas from: perforated cross pipesli) preferably arranged near the upper edges of the plates, so that a spray issues from the pipes Aonto -or toward the plates. This water maybe at any ordinary temperature suoli as 60 degrees Fahrenheit. .The gases enter the container from the' furnace at a high temperature, say 1500 degrees centigrade, and as they pass through the container the molecules of the gas are coole'd at a plurality of points, where they come into'contactl Withthe depositories or .baille plates. These plates have a relatively v largearea and they admirably perform their function of cooling the molecules of the gas. v`In practice the apparatus is regulated so i that substantially all the phosphorus will .be'

eliminated from the gasI before it passes from the container. With my apparatus the process canv be carried` on` continuously, be-

cause the sludge: which forms upon the plates drains into the dishl and'continuously overflows into the sludge tank. lVith my process it isY unnecessary to use a large, quantity ofwater; this is desirable as this vsimpliflesthe processof removing the phosphoric acid .fronrtbe sludge.

In order to remove the phosphoric acid from the sludge it is only necessary to mix it when desired with a 'larger quantity of Water which immediate'ly takes up the phosphoric. acidin solution, and after being allowed to settle scribed above 'is only one embodiment of the many forms or embodiments my process may take, and I do not Wish to be limited in the construction v-of my claims, nor in the practice of my process, to the particular process described above. i

What I claim is u 1. The process which consists in fusing phosphatic material and a flux in a nace to form a gas containing phosphorus, treating the gas passing from the furnace lwith a substance adapted to'deeompose the gas, and maintaining the temperatureof the gas above a predetermined point until substantially all the gas has been decomposed by said substance.

2. The` process which consists 1n fusing phosphatic material and a lluX in a furnace to form argas containing phosphorus,y

a' substance `adaptedfto decompose the gas,

locally cooling the molecules of the gas at a plurality of points and maintaining the temperature of the gas above the condensing point of said gas.

4. The process which consists in fusing phosphatic material and a flux in a furnace toform a gas containing phosphorus,

treating the gas passingfrom the furnace with a substance adapted to decompose the gas, .locally coolingthe molecules pf the gas at a plurality of points, and maintaining the temperature of the gas above the critical point of said gas, and causing a movement of the molecules of the gas to bring' them vinto contact with the' locally cooled points and facilitate theirdecom-posi-- tion.

5. The process which consists in causing a volume of phosphoric gas to come in contact with water to decompose the' gas, and maintaining the temperature of the said gas above a predetermined poirit until subStan-.

tially all the gas has been decomposed.

6. The process which consists in causing a volume of silicious phosphoric gas to come in Contact with Water to locally cool the molecules of the gas to decompose the same with said Water, and maintaining the ternperature of the said gas above a predetermined point.

7. The process which consists in advancing a column of hotphosphoric 'gas into contact with water at a plurality of points moving trans'velsely to tl1ediiectiox1 of ad# vence o the column of gas to decompose the gas.

8. The process which consists ineclvancing a column of hot phosphoric gas into- :zoutact with Water atea plurality of points moving transversely to the direction of advance of the column of gas to decompose the gas, and maintaining the temperature of the gas above a predetermined point While the decomposition is progressing.

' 9. The process which consists in fusing phosphatic material and a flux in a furnace to form a gas containing phosphoris, treating the gas passing from the furnace with a. substance which is adapted to decompose the gas and maintain the temperature of the gas above ZOG degrees centigrade until substan- 20 tiaily all the gas has been decomposed by the said substance.

10. The process which consists in fusing phcsplaatic material and a iux in a furnace to form a gas containing phosphorus, and

'passing the gas coming from the fui-nace into Contact with a substance adapted to decompose the gas Without reducing the temperature of tie body of the gas below a predetermined point.

ln testimony whereof I have .hereunto set 'my hand in presence of two subscribing Wit- 

